1. Field of the Invention
The present invention relates to an imaging lens device and a portable apparatus having an imaging function.
2. Description of the Related Art
A portable apparatus having an imaging function, such as a camera, uses an imaging lens device. The imaging lens device provides an imaging light beam path for leading an incident light beam to a predetermined imaging plane, and includes a plurality of lens units, which are arranged along and coaxial with the imaging light beam path, for focusing the incident light beam on the predetermined imaging plane.
Since the imaging lens device includes the plural lens units arranged along the imaging light beam path, the longitudinal length of the imaging lens device is relatively long so that the imaging lens device projects out from the body of the portable apparatus to a large degree.
In the conventional portable apparatus described above, the projecting imaging lens device deteriorates the portability of the conventional portable apparatus. In order to improve the portability of the conventional portable apparatus, Japanese Patent Application KOKAI Publication No. 2000-23002, published on Jan. 21, 2000, discloses causing one lens unit, which is located nearer to the predetermined imaging plane than the lens unit located most away from the predetermined imaging plane, to be movable between a first position, at which the one lens unit is coaxially located in the imaging light beam path, and a second position, at which the one lens unit is moved sideward and away from the imaging light beam path. The sideward movable lens unit is located at the first position when the imaging lens device is used for focusing the incident light on the predetermined imaging plane, and the sideward movable lens unit is located at the second position when the imaging lens device is not used for focusing the incident light on the predetermined imaging plane. While the sideward movable lens unit is located at the second position, the lens unit located farthest away from the imaging plane can be moved toward the predetermined imaging plane by the longitudinal length of the sideward movable lens unit so that the longitudinal length of the imaging lens device can be shortened.
However, in this published portable apparatus, it is difficult to arrange the sideward movable lens unit to be accurately coaxial with the imaging light beam path when the sideward movable lens is moved from the second position to the first position and stays at the first position.